In fuses for explosive projectiles and the like it is essential that the fuse not be armed prior to actual firing of the projectile or missile from a gun or the like. Further, the projectile or missile should travel a safe distance from the firing device before arming so that accidental explosions at the firing device cannot occur. Because the fuse is destroyed with the projectile, low cost is essential and, in addition, high reliability and safety must be incorporated. In prior art safety and arming mechanisms dashpots, escapements, chemical reactions, enertia motors and unwinder springs are utilized, all of which tend to reduce the miniaturization and reliability and increase the cost.